[feature request] Unix sockets

[MoritzMaxeiner]

I would really like to use libasync for IPC on Linux (specifically I would like to support it in i3ipc-d as the event dispatcher), but that does require support for unix sockets. Would it be possible to get support for those in libasync?

[etcimon]

Of course, will add within a month or so (once I have time!)

[MoritzMaxeiner]

Would it be possible for you give me an overview on what would need to be implemented?
Since I really need this for a project of mine (for which I wrote i3ipc-d in the first place), I tried to judge whether I would be able to implement this myself, but duplicating the tcp implementation and modifying it for unix did not appear to me to be very straight forward, as egrep -r revealed extensive references to tcp, i.e. even if I implemented unix.d, I am not able to easily make out how to plug in into the rest of libasync.

[etcimon]

That'll be a pre-initialized file descriptor, you could probably do it by passing a custom fd to AsyncTCPConnection using this constructor but I think AsyncEvent would be more of a fit for it, and you could probably use the regular c-style read/write functions on the socket descriptor. So, in both cases you'd need to create the unix socket beforehand using c-style examples. http://troydhanson.github.io/network/Unix_domain_sockets.html

I think it doesn't require a change in libasync, would have to test

[MoritzMaxeiner]

Okay, thank you for the pointers, I'll try may hand at it.

[MoritzMaxeiner]

First attempt of it is here, though I did have to rewrite some parts of AsyncEvent to support stateful sockets (I need connect and close events to be dispatched for unix domain sockets, but AsyncEvent did not support that yet): There is new argument in the constructor with which the caller tells AsyncEvent whether the given file descriptor is a stateful socket (like UDS) or not.
Note: It's not yet complete, i.e. kill is still missing, but this seems to already correctly dispatch connect/read/write/close events for UDS.

[etcimon]

Looks good so far, it seems to fit in nicely with the rest. Does this work in your tests?

[MoritzMaxeiner]

Cool, I was concerned that you may object to changing AsyncEvent like that.
Regarding your question: I'm currently using a minimal test like this:

auto loop = getThreadEventLoop;

auto unix = new AsyncUDSConnection(loop);
unix.peer = new UnixAddress("/var/run/user/1000/i3/ipc-socket.1234");
unix.run((code) {
    writeln(code);
});

while (true) {
    loop.loop(-1.seconds);
}

and the connect/read/close events seem to be dispatched correctly. I'll follow up with a more complete test soon.

[MoritzMaxeiner]

https://github.com/Calrama/libasync/commit/f756d97e74daff281ef1c126fdade80f42d91025 seems to be working as expected (complete UDS connection). Up next are a UDS listener, the promised test as an example (using both) and then making sure that this doesn't break either build or tests on non-UDS platforms

[etcimon]

Awesome

[MoritzMaxeiner]

https://github.com/Calrama/libasync/commit/1b80b608ac05ee02a015be7fce1aa39798c171c1 implements a UDS listener that seems to work fine. I followed the API for TCP Listener mostly, though I do require for the delegate that received the new UDSConnection to be nothrow (I could not think of any reason to allow exceptions here).

[MoritzMaxeiner]

https://github.com/Calrama/libasync/commit/9eb2d2533672e62224447a002c928744da6c4b5a has usage examples for UDS connection and UDS listener

[MoritzMaxeiner]

Whelp, it works.

[MoritzMaxeiner]

Since the above PR has been merged, I'll close this.